Parallel wire cable

ABSTRACT

A parallel wire cable is produced from a plurality of wires arranged in a bundle for use as a structural cable. Each wire in the plurality of wires is parallel to every other wire in the bundle, and each wire in the plurality of wires is tensioned to a tension value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/084,693 filed Apr. 12, 2011 and incorporated herein by reference inits entirety. This application also relates to European Patent No.2580407, which also claims priority to U.S. application Ser. No.13/084,693 filed Apr. 12, 2011.

BACKGROUND

Exemplary embodiments generally relate to static structures, to bridges,and to wireworking and, more particularly, to anchorage, to towers, toanchors, to cables, and to joining wire.

Parallel wire cables have long been desired as structural components.Parallel wire cables, for example, have been proposed for suspensionbridges. Parallel wire cables are capable of superior strength andstiffness when compared to conventional helically-wound strands andcable. Parallel wire cables, though, have proven elusive. Conventionaldesigns for parallel wire cables are far too costly to manufacture.Moreover, conventional manufacturing processes for parallel wire cablescreate troublesome tendencies to twist and coil, making handling andtransportation difficult and even unsafe.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The features, aspects, and advantages of the exemplary embodiments arebetter understood when the following Detailed Description is read withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic illustrating an operating environment, accordingto exemplary embodiments;

FIGS. 2 and 3 are more detailed schematics illustrating a structuralcable, according to exemplary embodiments;

FIG. 4 is a schematic illustrating tensioning of the structural cable,according to exemplary embodiments;

FIGS. 5 and 6 are schematics illustrating means for securing theplurality of wires, according to exemplary embodiments; and

FIG. 7 is a flowchart illustrating a method of manufacturing a parallelwire cable, according to exemplary embodiments.

DETAILED DESCRIPTION

The exemplary embodiments will now be described more fully hereinafterwith reference to the accompanying drawings. The exemplary embodimentsmay, however, be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein. Theseembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the exemplary embodiments to those ofordinary skill in the art. Moreover, all statements herein recitingembodiments, as well as specific examples thereof, are intended toencompass both structural and functional equivalents thereof.Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture (i.e., any elements developed that perform the same function,regardless of structure).

Thus, for example, it will be appreciated by those of ordinary skill inthe art that the diagrams, schematics, illustrations, and the likerepresent conceptual views or processes illustrating the exemplaryembodiments. Those of ordinary skill in the art further understand thatthe exemplary cables described herein are for illustrative purposes and,thus, are not intended to be limited to any particular manufacturingprocess and/or manufacturer.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes,” “comprises,”“including,” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. It will be understood thatwhen an element is referred to as being “connected” or “coupled” toanother element, it can be directly connected or coupled to the otherelement or intervening elements may be present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will also be understood that, although the terms first, second, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another.

FIG. 1 is a schematic illustrating an operating environment, accordingto exemplary embodiments. FIG. 1 illustrates a suspension bridge 10having a deck 12 supported by one or more pillars 14 (or “towers”) andby a structural cable 16. The structural cable 16 is anchored atopposite ends 18 and 20 by structural anchors 22. Tension in thestructural cable 16 helps support the weight of the deck 12. The designand structural behavior of the suspension bridge 10 is well-known tothose of ordinary skill in the art, so this disclosure will not providea further explanation of the suspension bridge 10.

FIGS. 2 and 3 are more detailed schematics illustrating the structuralcable 16, according to exemplary embodiments. FIG. 2 illustrates alongitudinal portion 30 of the structural cable 16. The structural cable16 comprises a plurality 32 of individual wires. The plurality 32 ofwires is illustrated as a bundle 36 having a circular shape 38. Theplurality 32 of wires, however, may be bundled in any cross-sectionalshape desired (such as hexagonal, triangular, or square). Eachindividual wire 40 in the plurality 32 of wires may be constructed ofany metallic and/or non-metallic material. An individual wire 40, forexample, may be 5 or 7 millimeter diameter steel wire (or any otherdiameter or gauge wire suitable for structural cable). Any of theindividual wires 40, however, may be constructed from carbon fibermaterial, composite material, or even electrical conductors. Eachindividual wire 40 is illustrated as having a circular cross-sectionalshape, but any of the wires 40 may have other cross-sectional shapes(such as hexagonal, triangular, polygonal, or even a variablecross-sectional shape).

As FIG. 3 also illustrates, the individual wires 40 are parallel. Eachwire 40 in the plurality 32 of wires is parallel to every other wire 40in the structural cable 16. The individual wires 40 are parallel alongtheir entire length L (illustrated as reference numeral 50) from one end18 of the structural cable 16 to the opposite end 20 of the structuralcable 16. Each wire 40 in the plurality 32 of individual wires may alsobe equal in length 50 to every other wire 40 in the structural cable 16.Each wire 40 in the structural cable 16, in other words, may be parallelto, and equal in length 50 to, every other wire 40. Because each wire 40is parallel to every other wire 40, no winding operation is required.The structural cable 16, in other words, need not be spirally orhelically wound.

FIG. 4 is another detailed schematic illustrating the structural cable16, according to exemplary embodiments. Here, though, only a few wires40 in the structural cable 16 are shown to simplify the illustration.Exemplary embodiments apply a tension value T (illustrated as referencenumeral 60) to each wire 40 in the structural cable 16. That is, eachwire 40 in the plurality 32 of individual wires may have an equal, ornearly equal, tension to every other wire 40 in the structural cable 16.As FIG. 4 illustrates, a tension value 60 is applied to an individualwire 62. An end 64 of the individual wire 62 is mechanically locked,held, or secured in a first fixture 66. The first fixture 66 isgenerically shown, as any apparatus or method may be used tofrictionally prevent the end 64 of the individual wire 62 from slippingas tension is applied. An opposite end 68 of the individual wire 62 isthen drawn or pulled to the desired tension value 60. The tension value60 may be measured with a dynamometer, but any apparatus or method ofmeasuring tension may be used. When the desired tension value 60 isattained, the opposite end 68 of the individual wire 62 is thenmechanically locked, held, or secured in a second fixture 70. Again, thesecond fixture 70 is generically shown, as any apparatus or method maybe used to maintain the tension value 60 applied to the individual wire62.

Exemplary embodiments pretension every wire 40 in the structural cable16. Once the tension value 60 is applied to the individual wire 62, thena second wire 80 in the structural cable 16 is selected. The second wire80 may be adjacent to the first-selected individual wire 62, or thesecond wire 80 may be circumferentially or radially distant. Regardlessof how or where the second wire 80 is chosen, the same tension value 60is applied to the second wire 80. An end 82 of the second wire 80 ismechanically locked, held, or secured in the first fixture 66, and anopposite end 84 is pulled to the desired tension value 60. Once thedesired tension value 60 is attained, the opposite end 84 of the secondwire 80 is then mechanically locked, held, or secured in the secondfixture 70.

Exemplary embodiments repeat this process or procedure for each wire 40in the structural cable 16. The tension value 60 is individually appliedor pulled to each wire 40 in the structural cable 16. Each wire 40 inthe plurality 32 of individual wires may thus have the equal tensionvalue 60 to every other wire 40 in the structural cable 16. In mostcases, of course, the tension value 60 will be a nominal value with apermissible variation. Exemplary embodiments thus individually pull eachwire 40 in the structural cable 16 to the nominal value within thepermissible variation (such as ±1%).

Tension is applied to each wire, not strands of wires. Methods are knownthat tension strands of plural wires. A strand, in the art of structuralcable, is defined as a group of multiple wires. Conventional methods areknown that apply tension to a strand of multiple wires. Exemplaryembodiments, in contradistinction, apply the tension value 60 to eachindividual wire 40 in the structural cable 16. Each wire 40 in theplurality 32 of individual wires has the equal tension value 60 as everyother wire 40 in the structural cable 16.

Individual pretensioning of each wire 40 will provide lighter, cheaper,and stronger cable designs. An individually-tensioned structural cablemay be made that weighs significantly less than conventional designs,but the strength of the structural cable is still greater thanconventional designs. Alternatively, exemplary embodiments may be usedto construct a structural cable that is similar in size to conventionaldesigns, but is substantially stronger to support greater loads and/orspans. Regardless, exemplary embodiments offer greater designalternatives that require less material cost.

The tension value 60 may be any value that suits performancerequirements. A low tension value 60, for example, may be applied toeach wire 40, but the plurality 32 of wires may be difficult to keepstraight and to maintain the desired length (illustrated as referencenumeral 50 in FIG. 3). Moreover, a low tension value 60 may make itdifficult to retain the desired geometry of the bundle (illustrated asreference numeral 36 in FIG. 2). In practice, then, a minimum of thetension value 60 may be the nominal load that overcomes any memory ormetallurgical cast of the wire coils. For example, if 9 gauge, 145 ksiyield wire (0.148 inch diameter) is used, the nominal load isapproximately 70 pounds per wire load (depending on the controltemperature). Other diameters of wires will have varying yieldstrengths, and the corresponding nominal loads are easily calculated andtested by those of ordinary skill in the art. In some cases the weightof the wire 40 itself may meet or exceed the nominal load. For example,if the wire 40 is long enough, its actual gravity load or the weight ofthe wire 40 may meet or exceed the calculated nominal tensioning load.

No tension adjustments are required. Exemplary embodiments repeatedlyapply the tension value 60 to each wire 40 in the structural cable 16.Once the tension value 60 is applied to a wire 40, though, the tensionvalue 60 need not be adjusted. Each wire 40 in the plurality 32 ofindividual wires may be tensioned without rechecking and adjusting apreviously-applied tension in another wire. The manufacturing of thestructural cable 16 may thus rapidly and sequentially apply the tensionvalue 60 to each wire 40 without revisiting previous measurements.

FIGS. 5 and 6 are schematics illustrating means for securing theplurality 32 of wires, according to exemplary embodiments. Once eachwire 40 in the structural cable 16 is tensioned to the tension value 60,the tension value 60 should be maintained for subsequent processing.Exemplary embodiments may thus seize the structural cable 16 to maintainthe tension value 60 in each wire 40. As FIG. 5 illustrates, a seizingforce S_(f) (illustrated as reference numeral 100) is applied along anouter circumference of the structural cable 16. For simplicity, FIG. 5only illustrates a segment or portion of the structural cable, but theseizing force 100 may be applied at multiple locations along thestructural cable 16. A fixture or press may apply the seizing force 100to maintain the tension value 60 in each wire 40. FIG. 6, for example,illustrates bands or seizings 102 spaced along the structural cable 16.The bands or seizings 102 are constructed and sized to circumferentiallyapply the seizing force 100 at multiple locations along the structuralcable 16. Regardless of how the seizing force 100 is applied, theseizing force 100 is applied inwardly of the first fixture 66 andinwardly of the second fixture 70. The seizing force 100 maintains thetension value 60 in each wire 40. The structural cable 16 may then becut to a desired overall length (illustrated as reference numeral 50 inFIG. 3). Attachments and/or sockets may then be added to each end (e.g.,illustrated as reference numerals 18 and 20 in FIGS. 1 and 3) of thestructural cable 16.

Exemplary embodiments may include an oxidation inhibitor. The plurality32 of wires may have a sacrificial coating or polymer coating that helpsprevent the structural cable 16 from corroding. One or more of theindividual wires 40 may additionally or alternatively include theoxidation inhibitor.

Exemplary embodiments may also include strands of the wires. Severalindividual wires 40 may be grouped or bundled into a strand, as isknown. Multiple strands may then be bundled to produce the structuralcable 16. Exemplary embodiments may thus be applied to each strand, suchthat each wire 40 in a strand is individually tensioned to the equaltension value 60.

FIG. 7 is a flowchart illustrating a method of manufacturing a parallelwire cable, according to exemplary embodiments. A wire is selected of aparallel wire structural cable (Block 200). The wire is frictionallyheld at one end (Block 202). An opposite end of the wire is pulled tothe tension value 60 (Block 204). The opposite end is then frictionallyheld to maintain the tension value 60 (Block 206). If wires remain totension (Block 208), then another wire is selected (Block 200) and thetension value 60 is applied, until a last wire is tensioned (Block 208).The parallel wire structural cable is secured or seized to maintaintension in the wires (Block 210). The parallel wire structural cable iscut to length (Block 212). An end attachment or socket is added (Block214). Corrosion protection may be added (Block 216).

While the exemplary embodiments have been described with respect tovarious features, aspects, and embodiments, those skilled and unskilledin the art will recognize the exemplary embodiments are not so limited.Other variations, modifications, and alternative embodiments may be madewithout departing from the spirit and scope of the exemplaryembodiments.

The invention claimed is:
 1. A process, comprising: i) frictionallyholding an end of a wire of a parallel wire structural cable; ii)pulling an opposite end of the wire to a tension value; iii)frictionally holding the opposite end of the wire to maintain thetension value; and iv) repeating i) through iii) for each other of aplurality of parallel wires in the parallel wire structural cableindividually and securing the parallel wires as a bundle to maintaintension.
 2. The process according to claim 1, further comprising cuttingthe parallel wire structural cable to a length.
 3. The process accordingto claim 1, further comprising adding an attachment to a cable end ofthe parallel wire structural cable.
 4. The process according to claim 1,further comprising adding a corrosion inhibitor to the wire.
 5. Theprocess according to claim 1, further comprising adding a corrosioninhibitor to the parallel wire structural cable.
 6. The processaccording to claim 1, further comprising seizing the parallel wires asthe bundle.